As a young medical student, Guevara traveled throughout Latin America and was transformed by the endemic poverty he witnessed. His experiences and observations during these trips led him to conclude that the region's ingrained economic inequalities were an intrinsic result of monopoly capitalism, neocolonialism, and imperialism, with the only remedy being world revolution. This belief prompted his involvement in Guatemala's social reforms under President Jacobo Arbenz Guzmán, whose eventual CIA-assisted overthrow solidified Guevara's radical ideology.

Later, in Mexico, he met Fidel Castro and joined his 26th of July Movement. In December 1956, he was among the revolutionaries who invaded Cuba under Castro's leadership with the intention of overthrowing U.S.-backed Cuban dictator Fulgencio Batista. Guevara soon rose to prominence among the insurgents, was promoted to Comandante, and played a pivotal role in the successful two year guerrilla campaign that deposed Batista. Following the Cuban revolution, Guevara reviewed the appeals of those convicted as war criminals during the revolutionary tribunals, ratifying sentences which in some cases utilized firing squads. Later he served as minister of industry and president of the national bank, before traversing the globe as a diplomat to meet an array of world leaders on behalf of Cuban socialism. He was also a prolific writer and diarist, composing a seminal manual on the theory and practice of guerrilla warfare, along with an acclaimed memoir about his motorcycle journey across South America. Guevara left Cuba in 1965 to incite revolutions first in an unsuccessful attempt in Congo-Kinshasa and later in Bolivia, where he was captured with the help of the CIA and executed.

Both notorious as a ruthless disciplinarian who unhesitatingly shot defectors and revered by supporters for his rigid dedication to professed doctrines, Guevara remains a controversial and significant historical figure. As a result of his perceived martyrdom, poetic invocations for class struggle, and desire to create the consciousness of a "new man" driven by "moral" rather than "material" incentives; Guevara evolved into a quintessential icon of leftist-inspired movements. Paradoxically and in contradiction with his ideology, Che's visage was also reconstituted as a global marketing emblem and insignia within popular culture. He has been mostly venerated and occasionally reviled in a multitude of biographies, memoirs, books, essays, documentaries, songs, and films. Time magazine named him one of the 100 most influential people of the 20th century, while an Alberto Korda photograph of him entitled Guerrillero Heroico (shown), was declared "the most famous photograph in the world."